SELLOS URSS

http://www.stamprussia.com/

http://filajavier.blogspot.com/

http://filajavier-monumentos-sovieticos.blogspot.com/

http://filateliaroja.blogspot.com

http://www.ricarduzz.com/2011/09/sellos-postales-de-la-urss.html

http://www.russian-stamps.narod.ru/pages/main.html